This invention relates to exercise apparatus, and particularly to an exerciser, such as a stationary exercise cycle, which is caused to control automatically the levels of exercise effort exerted by the user. It is directed primarily to a cycle exerciser loaded by a braking system, although the novel concepts disclosed are applicable to other types of exercisers.
In the field of stationary exercise cycles, one of the best known is sold under the trademark "Lifecycle". It provides a varying load by incorporating a "dynamic" brake, in the form of an alternator, whose resistance to user-caused rotation of the cycle is varied by varying field current in the alternator (Sweeney U.S. Pat. No. 4,358,105, assigned to Lifecycle). An alternator brake has certain benefits, including the fact that it supplies electrical current needed to operate the control and display circuitry of the exerciser.
The use of a dynamic brake has certain significant limitations. It is not effective until a minimum load level has been reached, a level which is high enough to substantially restrict the lower end of the operating range. Furthermore, it requires a multi-stage speed-increasing system to bring the alternator speed to the necessary RPM. The angular speed ratio of the alternator to the user-driven wheel needs to be about 25 to 1. Exercise cycles using alternator brakes generally have two drive stages in order to translate the 60-150 RPM pedaling speed into the 1500-3000 RPM operating range of the alternator. The power transmission system is a source of noise and maintenance (endurance) problems, because of the high force being transmitted. Such a system also requires expensive drives and bearings, and lacks the desired smoothness in its operation.
Some exercise cycles on the market use other types of brake control as load-determining devices. One type of brake used is an electrical energy brake, referred to as an "eddy current" brake. Its problems are similar to, and generally greater than, those of the dynamic brake.
Other exercise cycles use mechanical friction, which was used in this field prior to the dynamic brake. Dimick U.S. Pat. No. 3,621,948 (also assigned to Lifecycle) used a band brake, which exerted direct mechanical friction by engagement with the periphery of a flywheel. Another version of direct mechanical braking is the use of caliper brakes applied to opposite sides of the rotor, i.e., using the rotor as a disk in a disk brake.
Another type of friction brake arrangement is shown in Smith et al U.S. Pat. No. 4,592,544. In the latter patent, the user-driven pedals drive a set of gears, which in turn drive a flywheel rotating about a vertical axis. A manually-adjusted band brake engages the periphery of the flywheel.
Stationary exercise cycles using eddy current or friction brakes typically use a single speed-increasing stage, in order to increase the angular momentum of the braked flywheel. When the second stage or third stage is braked, the primary drive stage must transmit considerable torque at low speed, which typically requires a heavy-duty transmission, such as a chain and sprockets.
From extensive experimentation, and for the reasons stated above, the present inventors have concluded that it is highly desirable to have the braking force applied to a single-stage cycle, i.e., applied directly to the same rotating member (the "first stage") as the one driven directly by the user-operated pedals. Highly significant advantages result from eliminating the intermediate driving stage, or stages, between the cycle and the brake.
The present inventors are unaware of any automatically controlled commercial exercise cycle in which the braking force is applied to the first stage of the cycle.
A prior art search has yielded at least two patents showing stationary exercise cycles having first stage braking: Proctor U.S. Pat. No. 4,007,927 and Bowen U.S. Pat. No. 334,635. Proctor shows a caliper brake on a pedal-driven flywheel. Bowen shows a shoe brake engaging the peripheries of a pair of pedal-driven wheels. Both Proctor and Bowen use manual braking force adjustors. Neither of these patent disclosures can satisfy the need for a smoothly-functioning, high endurance, automatically-controllable stationary exercise cycle.